Hard-magnetic melt-spun R–Fe–B alloys on the base of light rare-earth metals (R=La, Nd)

Effects of La addition on microstructure and magnetic properties of LaxNd₃₃₋xFe₆₅.₉B₁.₁ (wt. %) melt-spun ribbons and isotropic bonded magnets were systematically studied. X-ray diffraction and DSC data revealed that addition of La led to the formation of highly refined and inhomogeneous La-rich phase. It was shown that the average grain size and volume fraction of the main magnetic (La,Nd)₂Fe₁₄B phase depend on La concentration. For better LaxNd₃₃₋xFe₆₅.₉B₁.₁x = 2.5 and 5 wt. % bonded samples, the room-temperature magnetic properties of Hci = 1343 kA/m and 1300 kA/m, and Br= 0.61 T and 0.614 T were obtained. Magnetic flux aging loss for alloys with appropriate La content (x = 5–10 wt. %) did not exceed 5 % in the range of 100–125°C, which is typical for conventional ternary Nd–Fe–B melt-spun magnets

Formation characteristics of Fe₃O₄ magnetic particles precipitated from aqueous solutions and their sorption properties

Effect of temperature and iron concentration in solution on the phase composition, particle size, and magnetization was studied. It is shown that amount of the magnetite phase increases with the temperature increase. The magnetization slightly decreases with increase in the initial iron concentration. It is found that, regardless of the deposition conditions, spherical particles are formed, the average size of which varies within 7 to 15 nm. Comparison between the for removal efficiency and sorption capacity of the particles with the magnetite and hematite phase for cobalt was carried out. The sorption capacity of the particles is essentially independent of the phase composition and is about 18 mg/g for cobalt. For preparation of sorption material based on Fe₃O₄ magnetic particles, it is recommended to carry out the precipitation at the temperature of not lower than 80°C and the concentration of iron in solution of 0.15 to 0.3 M. The resulting particles comprise not less than 90 wt. % of magnetite phase and are characterized by magnetization of 65 to 70 A·m²/kg

Transparent ceramics of yttrium-aluminum garnet (Y₃Al₅O₁₂) from nanocrystalline powders obtained by co-precipitation

Nanosized powders of yttrium-aluminum garnet Y₃Al₅O₁₂, (YAG) have been obtained by chemical co-precipitation. The effect of the powder structure and morphology on the compactibility and sinterability has been studied. The optimal combination of these properties has been found in the YAG powder having the average grain size of 80 nm synthesized at 1200°C. Using the vacuum sintering at 1750°C, the transparent Y₃Al₅O₁₂ ceramics has been obtained having the density 99.9% of theoretical value and the transmission coefficient 60% in the wavelength range of 400 to 800 nm.Методом хімічного співосадження синтезовано нанорозмірні порошки ітрійалюмінієвого гранату Y₃Al₅O₁₂ (ІАГ). Вивчено вплив структури та морфології порошків на їх пресуємість та спікливість. Встановлено, що оптимальні сполучення цих характеристик має порошок ІАГ із середнім розміром зерна 80 нм, синтезований при температурі 1200°С. Методом вакуумного спікання при 1750°С одержано прозору кераміку Y₃Al₅O₁₂ із щільністю 99,9% від теоретичної та коефіцієнтом пропускання 60% в області довжин хвиль 400-800 нм.Методом химического соосаждения получены наноразмерные порошки иттрий-алюминиевого граната Y₃Al₅O₁₂ (ИАГ). Изучено влияние структуры и морфологии порошков на их прессуем ость и спекаем ость. Установлено, что оптимальным сочетанием этих характеристик обладает порошок ИАГ со средним размером зерна 80 нм, синтезированный при температуре 1200°С. Методом вакуумного спекания при 1750°С получена прозрачная керамика Y₃Al₅O₁₂ с плотностью 99,9% от теоретической и коэффициентом пропускания 60% в области длин волн 400-800 нм